Compatibility of different measurement techniques of global solar radiation and application for long-term observations at Izaña Observatory

Abstract

Abstract. A 1-year inter-comparison of classical and modern radiation and sunshine duration (SD) instruments has been performed at Izaña Atmospheric Observatory (IZO) located in Tenerife (Canary Islands, Spain) starting on 17 July 2014. We compare daily global solar radiation (GSR H ) records measured with a Kipp & Zonen CM-21 pyranometer, taken in the framework of the Baseline Surface Radiation Network, with those measured with a multifilter rotating shadowband radiometer (MFRSR), a bimetallic pyranometer (PYR) and GSR H estimated from sunshine duration performed by a Campbell-Stokes sunshine recorder (CS) and a Kipp & Zonen sunshine duration sensor (CSD). Given that the BSRN GSR H records passed strict quality controls (based on principles of physical limits and comparison with the LibRadtran model), they have been used as reference in the inter-comparison study. We obtain an overall root mean square error (RMSE) of ∼ 0.9 MJm −2 (4 %) for PYR and MFRSR GSR H , 1.9 (7 %) and 1.2 MJm −2 (5 %) for CS and CSD GSR H , respectively. Factors such as temperature, relative humidity (RH) and the solar zenith angle (SZA) have been shown to moderately affect the GSR H observations. As an application of the methodology developed in this work, we have re-evaluated the GSR H data time series obtained at IZO with two PYRs between 1977 and 1991. Their high consistency and temporal stability have been proved by comparing with GSR H estimates obtained from SD observations. These results demonstrate that (1) the continuous-basis intercomparison of different GSR H techniques offers important diagnostics for identifying inconsistencies between GSR H data records, and (2) the GSR H measurements performed with classical and more simple instruments are consistent with more modern techniques and, thus, valid to recover GSR H data time series and complete worldwide distributed GSR H data. The inter-comparison and quality assessment of these different techniques have allowed us to obtain a complete and consistent long-term global solar radiation series at Izaña.

The Role of Clouds in Global Radiation Changes Measured in Israel during the Last Sixty Years

“…The greater accuracy to be expected for the monthly and annual values analyzed in this study is limited by the 0.3% uncertainty in the World Radiometric Reference and the loss of accuracy involved in its transfer by calibration to the pyranometers in routine use. Error terms of 5% and 2% respectively have been estimated for monthly and annual values of E g ↓ [18] [19].…”

Solar radiation measurements in the United States between 1916 and 1949 document widespread brightening in the mid‐20th century

“…The calibration procedure used for the Callendar Sunshine Receiver, the pyranometer which provided the earliest and longest United States series of measurements, has been described in detail (Kimball, ), The Eppley pyranometers used at the majority of the measurement sites analysed (Hand, ) were calibrated by the manufacturers. As the uncertainty of the 1913 Smithsonian scale was 2% (WMO, ) it seems reasonable to assume a similar value for the uncertainty of measured annual mean values, comparable with that currently assigned to network measurements of E g ↓ (Gilgen et al ., ; Garcia et al ., ).…”

“…These include 65 stations of the Japanese national network of climate stations covering an area extending from 25° to 45°N and from 125° to 140°E (Stanhill and Cohen, ). Increases in sunshine duration were measured at eight sites in Taiwan (Liu et al ., ), at 17 Swiss sites (Sanchez‐Lorenzo and Wild, ) and at Izana, a mountain top observatory in Tenerife, an island in the Atlantic Ocean, some 300 km west of the coast of Africa (Garcia et al ., ).…”

Description of the Baseline Surface Radiation Network (BSRN) station at the Izaña Observatory (2009–2017): measurements and quality control/assurance procedures

“…The measured input parameters used in the LibRadtran model simulations are shown in Table 6. The model input parameters -precipitable water vapor (PWV), aerosol optical depth (AOD), total ozone column and surface albedo -are measured at IZA (García et al, 2014(García et al, , 2018. The straightforward comparison between the instantaneous and daily SWD, DIR and DIF simulations and measurements shows an excellent agreement (Fig.…”

“…Following the BSRN recommendations, the instantaneous clear-sky periods detected are simulated and compared with instantaneous and daily radiation measurements. The RTM model used is LibRadtran (http://www.libradtran.org, last access: 7 February 2019; Mayer and Kylling, 2005;Emde et al, 2016), which has been extensively tested at IZA (García et al, 2014(García et al, , 2018. The measured input parameters used in the LibRadtran model simulations are shown in Table 6.…”